The present invention is related to foam-in-place packaging. Foam-in-place packaging is a useful alternative to packaging fragile or other items with loose, friable or dunnage-type materials. As known to those familiar with the packaging arts, there are a number of techniques for packaging fragile articles, most of which have associated advantages and disadvantages.
One advantageous method of easily packaging uniquely shaped items that may not otherwise be packaged in generally rectangular shipping containers, such as cardboard boxes, is referred to as foam-in-place packaging. In its overall application, a foam-in-place packaging system is one in which an item to be cushioned is placed into a container, such as a cardboard box, and then a foamable composition is added to the container. Typical foamable compositions include urethane precursors which, when mixed, generate polyurethane, carbon dioxide, and water vapor. As the urethane forms and hardens, these gases are concurrently generated so that by the time the urethane sets (generally a relatively short period of a few minutes or less) it takes the form of a polymer foam that has expanded to fill the void spaces in the container and to thereby cushion the item being packaged.
In many packaging applications, however, the item being packaged may not be able to tolerate direct contact with either the foam precursors or the foam itself. Furthermore, because the foaming, hardening polymer will tend to expand into all open spaces, some of it may become lodged in undesirable portions of the item being packaged.
Therefore, an early method of foam-in-place packaging included wrapping an item in plastic film prior to addition of the foamable composition. The plastic film protected the items from direct contact with the foamable composition, but was flexible enough so that the foamable composition could still expand and occupy the majority of void space in the container and thereby provide the desired custom-shaped cushion.
In many situations, however, the use of plastic-wrapped items still require that the plastic be placed over the item by hand, and the foam be hand injected by an operator controlling a nozzle connected to a supply of the foam precursors.
Therefore, the need was recognized and addressed to provide a more automated system of foam-in-place packaging. The results have been generally successful and include various devices, including a number assigned to the assignee of the present application. These include the device and method taught in U.S. Pat. No. 4,674,268 to Gavronski, No. 4,800,708 to Sperry, and No. 4,854,109 to Pinarer. Each of these patents disclosed a method of producing a plastic bag that was concurrently filled with a foamable composition. Such a bag can be immediately dropped into a packaging carton as the foamable composition begins to create the foamed polymer. Because the foam and the foamable composition is trapped in the bag, contact with the items being packaged is nicely avoided. At the same time, the only manual operation required--indeed if any--is to place such bags in appropriate containers with items to be cushioned.
Based on the success of these devices, newer devices have been developed which produce generally similar bags, but at greatly increased speed and efficiency. One such recent development is set forth in copending application Ser. No. 07/766,810, filed Sep. 26, 1991, now U.S. Pat. No. 5,376,219 to Sperry et al. for "High Speed Apparatus For Forming Foam Cushions For Packaging Purposes." The contents of this application are incorporated entirely herein by reference.
The device set forth in the '810 application is, however, most useful for large scale, high volume packaging operations, and its advantages and suitability for such are appropriate set forth in the '810 application. There are a number of situations, however, where the particular end user does not require the ability to produce large numbers of foam-in-place cushions on a constant basis, but would still appreciate the opportunity to take advantage of the desirable features of foam-in-place packaging. To date, all such foam-in-place packaging apparatus have been fairly large and somewhat sophisticated. Therefore, there exists the need for a straightforward, serviceable, compact and efficient device for forming foam-in-place cushions on either a continuous or intermittent basis, and of which those requiring such services can take maximum advantage.